1. Field of the Invention
The present invention relates to a method of manufacturing electronic elements and, more particularly, to a method of manufacturing electronic elements having external electrodes at their ends, such as laminated capacitors, chip resistors, and chip inductors.
Conventionally, in manufacturing electronic elements having external electrodes, an element 2 is dipped into a layer 1 of electrode material paint, as shown in FIG. 11. Thereby, a film 3 of the electrode material paint is formed at one end of the element 2, as shown in FIG. 12. By firing the element 2 having the film 3 of the electrode material paint, an electronic element having external electrodes is formed.
However, when such a method is used, the amount of the electrode material paint that is adhered to the element varies, and if the amount is too large, the thickness of the film 3 of the electrode material paint may sometimes become large, as shown in FIG. 12. When firing the element in such a condition, the external electrode of the electronic element becomes thicker than is necessary, and the cost of the electrode material rises. Furthermore, when the amount of the electrode material paint that is adhered to the element varies, the thickness of the external electrode of the electronic element also varies.
It has been considered that in order to remove an excessive amount of the electrode material paint that is adhered onto the element, the element is pressed on a flat surface having no electrode material paint layer, as shown in FIG. 13, and the excessive amount of the electrode material paint is removed and collected. However, in such a method, excess electrode material paint than is necessary could be removed, and the outer shape of the electrode could be distorted as shown in FIG. 14. Therefore, an external electrode having a uniform thickness can not be obtained. Moreover, in such a case, the external electrode could have an insufficient thickness, and thus a low level of heat resistance when soldered.
Furthermore, because electrode material paint of a relatively high viscosity is used, bubbles are sometimes formed on the under-surface of the element 2 when dipping the element 2 into the layer 1 of the electrode material paint. In this case, the electrode material paint can not discharge the bubbles on the under-surface of the element 2 when the element 2 is pulled up from the layer 1 of the electrode material paint, and thus a void 4 sometimes remains in the film 3 as shown in FIG. 15. It is frequently difficult to remove such a void even when dipping of the element 2 is repeated several times into the electrode material paint. If the element in such a condition is fired, voids remain in the external electrode of the electronic element, and it is difficult to locate out these voids from the outside. Sometimes, silver elution from the external electrode occurs due to consumption of silver when the external electrode is soldered to a printed circuit board, and a defect of connection frequently becomes evident. And, it is only after such a condition takes place that the defect of the electronic element is found.